NEW ORLEANS -- Contraflow began on Louisiana interstates Sunday, according to WDSU-TV. Just hours before, New Orleans Mayor Ray Nagin announced a mandatory evacuation for the city, scheduled for Sunday.

The reversal of some expressway lanes, making all lanes of the expressways lead out of town, will help thousands of local evacuees packing the roads escape the path of Hurricane Gustav. Meanwhile, officials gave advice on which way to leave town, including heading north if possible to avoid congestion on Interstate 10. Traffic in Mississippi was also heavy Sunday morning as evacuees fled the coast there.

"There are some sig delays on I-12 east as you get farther into Mississippi," said Mark Lambert, of the Louisiana Department of Transportation and Development.

Because of significant backups on eastbound Interstate 12, Lambert said "We're working with Mississippi and now allowing traffic to get onto Interstate 10 eastbound. Were hoping that that will help relieve some congestion on I-12 east."